1. Field of the Invention
The present invention relates to a semiconductor integrated circuit which can be suitably used in case that two devices, for example, are connected with each other through an optical transmission path or line and an optical signal is transmitted between the two devices (an optical signal is sent from one to the other or received by any one of them) over the optical transmission path to operate one or both of the devices.
2. Description of the Related Art
Many of semiconductor device testing apparatus (commonly called IC tester) for testing various types of semiconductor devices including semiconductor integrated circuits (IC) have a semiconductor device transporting and handling apparatus (commonly called handler) connected thereto for transporting various types of semiconductor devices to be tested (commonly called DUTS) to a test section for testing them, and carrying the tested semiconductor devices out of the test section for transport to a desired location. In such type of the semiconductor device testing apparatus, the section thereof called xe2x80x9ctest headxe2x80x9d which is disposed in the test section of the handler is formed separately from the testing apparatus proper, and a signal transmission path or line such as a cable connects therebetween.
The testing apparatus proper and the test head have a semiconductor integrated circuit used therein, respectively, and the operation rate or speed of a semiconductor device which is testable by the testing apparatus is determined depending upon the transmission rate of a signal transmitting between them. In other words, if the transmission rate of a signal transmitting between the testing apparatus proper and the test head cannot be made high, it is impossible to test a semiconductor device having high operating speed or rate.
It is needless to say that the more the transmission rate of a signal transmitting between not only the semiconductor device testing apparatus proper and the test head but also two devices each having a semiconductor integrated circuit used therein is made high, the more it is desirable. For this end, recently, an optical signal is used as a signal transmitting between a plurality of devices each having a semiconductor integrated circuit used therein to make the transmission rate of the signal high.
FIG. 12 is a block diagram showing one circuit construction of the conventional transmitting side device and the conventional receiving side device adopted in case of transmitting an optical signal between two devices each having a semiconductor integrated circuit used therein. This case shown in FIG. 12 is one in which data (a signal) is transmitted by use of an optical signal from the transmitting side device A to the receiving side device B. The transmitting side device A comprises a light emitting element 11 such as a laser diode, a light emitting diode or the like, a light emitting element driver circuit 12 for supplying a drive signal to the light emitting element 11, and a semiconductor integrated circuit 13 for supplying data (a pulse signal for example) to be transmitted to the light emitting element driver circuit 12.
The receiving side device B comprises a light receiving element 15 such as a photodiode, phototransistor or the like, a current detector circuit 16 for detecting an output current from the light receiving element 15 to convert it into data corresponding to the original data, and a semiconductor integrated circuit 17 for receiving an output signal from the current detector circuit 16 tc process it in a predetermined manner. The transmitting side device A and the receiving side device B are optically connected with each other by an optical transmission path or line 14 formed by an optical fiber. Usually, a PIN photodiode or avalanche photodiode (APD) is used as the light receiving element 15.
In the construction mentioned above, when data to be transmitted is applied to the light emitting driver circuit 12 from the semiconductor integrated circuit 13 which forts a signal source in the transmitting side device A, the light emitting element driver circuit 12 applies a drive signal corresponding to this data to the light emitting element 11 where the data is converted into an optical signal. The optical signal is transmitted through the optical transmission path 14 to the receiving side device B in which the light receiving element 15 converts the received optical signal into a current signal. The current signal is detected by the current detector circuit 16 which converts it into data corresponding to the original data. The data is given to the semiconductor integrated circuit 17 to process it in a predetermined manner.
Generally, there are often the cases a semiconductor integrated circuit is constituted by a plurality of CMOSs (Complementary Metal-Oxide Semiconductor) because a CMOS structure integrated circuit can be manufactured with high degree or high density in integration so that it can be miniaturized, the manufacture thereof is easy, the power consumption thereof is little, and it can be manufactured by low cost. In FIG. 12, the semiconductor integrated circuits 13 and 17 (they are Large Scale Integrated circuits, in this example) are constituted by many CMOSs, respectively. On the contrary, the light emitting driver circuit 12 and the current detector circuit 16 are constituted by a plurality of bipolar transistors, GaAs field effect transistors or the like suitable for high speed operation, respectively.
Heretofore, the purpose of signal transmission has been directed to a long-distance and high density transmission of signals such as, for instance, signal transmission in a main line or trunk line system of a communication network. For this end, it is necessary to carry information content as much as possible on one optical fiber, and hence high rate signal transmission of several Gbps (gigabits/sec) to several tens Gbps per one optical fiber is requested. As a result, bipolar transistors, GaAs field effect transistors or the like suitable for high speed operation have been inevitably used in the past.
Accordingly, as shown in FIG. 12, in addition to the semiconductor integrated circuits 13 and 17, the light emitting element driver circuit 12 and the current detector circuit 16 are provided in the transmitting side device A and the receiving side device B separately from the semiconductor integrated circuits 13 and 17, respectively. Consequently, there are needed additional spaces for accommodating the light emitting element driver circuit 12 and the current detector circuit 16 on the semiconductor chips on which the semiconductor integrated circuit 13 and 17 are formed, respectively. Moreover, there is a necessary to connect between the semiconductor integrated circuit 13 and the light emitting element driver circuit 12 and between the semiconductor integrated circuit 17 and the current detector circuit 16 by outer conductive paths, respectively, which results in a defect that power consumption is considerably increase.
In particular, in case that many optical transmission paths of several hundred to several thousand channels are provided between the transmitting side device A and the receiving side device B, spaces for accommodating the light emitting element driver circuits 12 and the current detector circuits 16 and the amount of power consumption are increased more and more with the number of channels increased. As a result, riot only the power consumption is greatly increased but also a large space is needed, and hence it is a big obstacle in miniaturizing the transmitting side device A and the receiving side device B.
However, in case of a short-distance and parallel data transmission as in the semiconductor device testing apparatus described before, or between frames or racks or in a frame or rack of a parallel computer or the like, the transfer or transmission rate is 1 to 2 Gbps at its maximum, but a great number of signals must be treated. In addition, such apparatus of the type transmitting an optical signal must has its size, power consumption, price, and the like equal to or lower than those of the conventional apparatus of the type transmitting an electrical signal. For this reason, the semiconductor integrated circuits are required to have a small size, low power consumption and low price. Consequently, it is necessary to use semiconductor integrated circuits of CMOS structure which are now the main products in large scene integrated circuits. Moreover, the light emitting element driver circuit and the current detector circuit must be formed in associated integrated circuits of CMOS structure integrally therewith, respectively.
An object of the present invention is to provide a semiconductor integrated circuit in which a space for accommodating a light emitting element driver circuit or a current detector circuit can be reduced even if the number of channels connecting between a plurality of devices each having a semiconductor integrated circuit used therein.
An another object of the present invention is to provide a semiconductor integrated circuit in which a semiconductor integrated circuit serving as a signal source and a light emitting element driver circuit are formed as a semiconductor integrated circuit of one chip having CMOS structure and a current detector circuit and a semiconductor integrated circuit serving to process a signal are formed as a semiconductor integrated circuit of one chip having CMOS structure thereby making electric power relating to signal transmission between these circuits substantially zero, resulting in much reduction of power consumption.
In the first aspect of the present invention, there is provided a semiconductor integrated circuit wherein a signal source circuit for generating a signal to be transmitted, a light emitting element driver circuit for supplying a signal outputted from the signal source circuit to a light emitting element disposed at a position outside the semiconductor integrated circuit as a drive signal, and a light emitting element connecting terminal connected to the output end of the light emitting element driver circuit and to which the light emitting element is connected are integrally formed on one semiconductor chip.
Also, there is provided a semiconductor integrated circuit wherein a light receiving element connecting terminal supplied with a current outputted from a light receiving element disposed at a position outside the semiconductor integrated circuit, a current detector circuit the input end of which is connected to the light receiving element connecting terminal, and a signal processing circuit for receiving a signal outputted from the current detector circuit to process it in a predetermined manner are integrally formed on one semiconductor chip.
In a preferred embodiment, the semiconductor chip is constituted by CMOSs.
According to the construction of the present invention as mentioned above, since the arrangement is such that the light emitting element driver circuit or the current detector circuit is integrally built in the semiconductor integrated circuit serving as a signal source or the semiconductor integrated circuit constituting a signal processing circuit, the transmitting side device or the receiving side device is completed only by connecting a light emitting element or a light receiving element to the light emitting element connecting terminal or the light receiving element connecting terminal provided in the semiconductor integrated circuit. Therefore, the transmitting side device or the receiving side device is constituted by parts of the semiconductor integrated circuit and the light emitting element or the semiconductor integrated circuit and the light receiving element, resulting in decreasing the occupation of a space. In addition, by forming the light emitting element driver circuit or the current detector circuit in the associated semiconductor integrated circuit of CMOS structure, The transmitting side device or the receiving side device can be miniaturized, and power consumption can be reduced.
In the second aspect of the present invention, there is provided a semiconductor integrated circuit wherein a signal source circuit for generating a signal to be transmitted, a light emitting element driver circuit for supplying a signal outputted from the signal source circuit to a light emitting element disposed at a position outside the semiconductor integrated circuit as a drive signal, a light emitting element connecting terminal connected to the output end of the light emitting element driver circuit and to which the light emitting element is connected, a light receiving element connecting terminal supplied with a current outputted from a light receiving element disposed at a position outside the semiconductor integrated circuit, a current detector circuit the input end of which is connected to the light receiving element connecting terminal, and a signal processing circuit for receiving a signal outputted from the current detector circuit to process it in a predetermined manner are integrally formed on one semiconductor chip.
In a preferred embodiment, a plurality of the light emitting element driver circuits, a plurality of the light emitting element connecting terminals, a plurality of the signal source circuits, a plurality of the light receiving element connecting terminal, a plurality of the current detector circuit, and a plurality of the signal processing circuit are provided. In addition, the semiconductor chip is constituted by CMOSs.
In the third aspect of the present invention, there is provided a semiconductor integrated circuit wherein in a device for transmitting a signal inputted to a semiconductor integrated circuit and a signal outputted from the integrated circuit to be transmitted to an other circuit by use of an optical signal, a light emitting element driver circuit and a detector circuit for detecting a current outputted from a light receiving element both of which are used in transmitting the optical signal are integrally formed on one semiconductor chip.
It is preferred that the semiconductor chip is constituted by CMOSs.